Control apparatus for vehicle having fuel cell mounted thereon

ABSTRACT

A control apparatus ( 6 ) for a vehicle (V) which includes a fuel cell ( 11 ) for generating electricity, auxiliary equipment ( 12 ) of the fuel cell ( 11 ), a secondary battery ( 3 ) to be charged with electricity generated by the fuel cell ( 11 ), and a motor ( 1 ) to be fed with electricity from the fuel cell ( 11 ) and/or the secondary battery ( 3 ). The control apparatus ( 6 ) commences start-up of the fuel cell ( 11 ), supplying electricity from the secondary battery ( 3 ) to the auxiliary equipment ( 12 ), monitors status of the fuel cell ( 11 ), and as the status meets a predetermined condition, computes an electric power at which the secondary battery ( 3 ) discharges electricity, based on state of charge of the secondary battery ( 3 ) and remaining time to completion of the start-up of the fuel cell ( 11 ), and supplies electricity from the secondary battery ( 3 ) to the motor ( 1 ) at the computed electric power.

TECHNICAL FIELD

The present invention relates to a control apparatus for a vehicle whichhas a fuel cell mounted thereon, and a driving motor for generatingrunning torque of the vehicle to be fed with electricity generated bythe fuel cell.

BACKGROUND ART

In a vehicle with a fuel cell mounted thereon, at the start of running,electricity stored in a secondary battery is supplied to a driving motorwhich generates running torque and to auxiliary equipment of the fuelcell for starting up the fuel cell.

Japanese Patent Laid-Open Publication No. 2002-289209 discloses a fuelcell system in which a secondary battery is used as a power source for adrive motor until system start-up operation is completed. While thevehicle is standing with the fuel cell system running, a target state ofcharge of the secondary battery is set higher than usual so that thesecondary battery is charged sufficiently and the motor can be fed withelectricity from the secondary battery during the subsequent systemstart-up.

Japanese Patent Laid-Open Publication No. 2002-343401 discloses anenergy output control system for a vehicle equipped with an engine and afuel cell, which determines whether to start up the fuel cell based ondistance from the present position to the destination. If the distancefrom the present position to the destination is shorter than apredetermined distance, it is determined not to start up the fuel cell.In this case, only the engine is used as a drive source.

DISCLOSURE OF THE INVENTION

In the fuel cell system in the former publication, in order to realizethe running of the vehicle while the fuel cell is being started up, itis necessary to supply the electricity from the secondary battery to thedrive motor and the auxiliary equipment for starting up the fuel cell.In order to obtain sufficient and stable electricity supply, it isnecessary to increase the capacity of the secondary battery, and as aresult of this, cost is increased. Moreover, when the vehicle isstopped, it is necessary to have the fuel cell to continue itselectricity generation until the secondary battery is sufficientlyrecharged, and accordingly, a standby time is required before a completestop of the system.

Meanwhile, in the system in the latter publication using an engine as apower source as well as a fuel cell, a secondary battery may berelatively small in capacity. However, if the electric power requiredfor the drive motor and that of the auxiliary equipment risesimultaneously, it is possible that too much electric power is takenfrom the secondary battery, causing an overdischarge thereof.Particularly, if the auxiliary equipment consuming much power is startedduring the start-up of the fuel cell, and concurrently, the electricpower required by the drive motor reaches the maximum, the possibilityof the overdischarge increases.

In order to prevent the overdischarge as described above, it isnecessary to adopt a secondary battery which has not only a largecapacity but also a large discharge capability.

The present invention was made in the light of the problem. An object ofthe present invention is to provide a control apparatus for a vehiclewith a fuel cell mounted thereon, which prevents the overdischarge ofthe secondary battery and ensures stable generation of running torquerequired, when the vehicle is running only by the electricity charged tothe secondary battery during the start-up of the fuel cell.

An aspect of the present invention is a control apparatus for a vehiclewhich comprises a fuel cell for generating electricity, auxiliaryequipment of the fuel cell, a secondary battery to be charged withelectricity generated by the fuel cell, and a motor to be fed withelectricity from the fuel cell and/or the secondary battery, wherein thecontrol apparatus commences start-up of the fuel cell, supplyingelectricity from the secondary battery to the auxiliary equipment,monitors status of the fuel cell, and as the status meets apredetermined condition, computes an electric power at which thesecondary battery discharges electricity, based on state of charge ofthe secondary battery and remaining time to completion of the. start-upof the fuel cell, and supplies electricity from the secondary battery tothe motor at the computed electric power.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the accompanyingdrawings wherein:

FIG. 1 is a block diagram showing a configuration of a fuel cell vehicleto which the present invention is applied;

FIG. 2 is a flowchart showing processes of vehicle start-up procedure inthe fuel cell vehicle to which the present invention is applied;

FIG. 3 is a flowchart showing processes for selecting a start-upprocedure of a fuel cell stack in the vehicle start-up procedure;

FIG. 4 is a flowchart showing processes for computing a runningpermission determining code in the vehicle start-up procedure;

FIG. 5 is a graph showing relationships between state of charges of asecondary battery and the running permission codes, which are differentfor each start-up procedure in the vehicle start-up procedure;

FIG. 6 is a flowchart showing processes for setting an upper limit valueof electric power to be discharged from the secondary battery in thevehicle start-up procedure;

FIG. 7 is a graph showing relationships between start-up status codes SCand time required to complete the start-up operation in the vehiclestart-up procedure;

FIG. 8 is a graph showing temporal variation of the start-up statuscodes SC, which are different for each start-up procedure in the vehiclestart-up procedure;

FIG. 9 is a graph for explaining process for setting KP in the vehiclestart-up procedure;

FIG. 10 is a graph showing a relationship between a remaining time tocomplete the start-up operation and the upper limit value of theelectric power to be discharged from the secondary battery in thevehicle start-up procedure; and

FIGS. 11A to 11D are timing charts for explaining an operation of thefuel cell vehicle when the vehicle start-up procedure is performed: FIG.11A shows the start-up status code SC; FIG. 11B shows a charge/dischargecurrent of the secondary battery; FIG. 11C shows a voltage of thesecondary battery; and FIG. 11D shows SOC of the secondary battery.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be explained below withreference to the drawings, wherein like members are designated by likereference characters.

In a fuel cell vehicle V shown in FIG. 1, electricity generated by afuel cell system 2 is supplied to a drive motor 1 and stored in asecondary battery 3. The drive motor 1 is supplied with electricity fromthe fuel cell system 2 or the secondary battery 3, and generates torquefor running the fuel cell vehicle V.

The fuel cell system 2 includes a fuel cell stack 11 which generateselectricity to be supplied to the drive motor 1, auxiliary equipment 12for electricity generation of the fuel cell stack 11, and a fuel cellcontrol unit 13 which controls the auxiliary equipment 12.

The drive motor 1 is, for example, a three-phase current motor.Direct-current power from the fuel cell system 2 or the secondarybattery 3 is converted into desired alternate-current power by anunillustrated inverter, and the alternate-current power is supplied tothe drive motor 1.

A main switch 4 is provided on a power line between the drive motor 1and the fuel cell stack 11, and a voltage inverter 5 is provided betweenthe secondary battery 3 and the auxiliary equipment 12. Moreover, avehicle control unit 6 which controls operations of the drive motor 1,the fuel cell system 2 and the secondary battery 3 is provided.

The fuel cell stack 11 generates electricity through electrochemicalreaction between fuel gas which contains a large amount of hydrogen andoxidant gas which contains oxygen. The fuel cell stack 11 is a pluralityof fuel cells stacked on one another, each of which includes a membraneelectrode assembly sandwiched between a pair of separators. Each of themembrane electrode assemblies has an air electrode to be supplied withair as the oxidant gas, a hydrogen electrode to be supplied withhydrogen gas as the fuel gas, and a solid polymer electrolyte membranesandwiched therebetween. Electricity is generated in this fuel cellstack 11 in a manner that the hydrogen in the hydrogen gas emitselectrons at the hydrogen electrode, protons (H⁺) thus produced aretransported through the polymer electrolyte membrane to the air(cathode) electrode, where the protons react with oxygen to form water(H₂O).

The auxiliary equipment 12 includes a hydrogen supply system forsupplying the hydrogen gas to the fuel cell stack 11, which isconstituted of a hydrogen storage tank, a hydrogen pressure regulationvalve, a circulation pump, and pipings, an air supply system forsupplying the air to the fuel cell stack 11, which is constituted of acompressor, an air pressure regulation valve, and pipings, and a coolantcirculation system for regulating temperature of the fuel cell stack 11.

For starting the electricity generation of the fuel cell stack 11, theauxiliary equipment 12 are supplied with the electricity from thesecondary battery 3 after voltage thereof are regulated by the voltageinverter 5. The respective components of the auxiliary equipment 12 arecontrolled by control signals from the fuel cell control unit 13, andthe auxiliary equipment 12 are thus operated so as to supply hydrogenand air corresponding to a power output required for the fuel cell stack11.

The fuel cell control unit 13 controls the electricity generatingreaction of the fuel cell stack 11 through controlling the auxiliaryequipment 12. This fuel cell control unit 13 stores, in an unillustratedstorage unit such as ROM (Read Only Memory), programs describing aseries of processing procedures for starting up the fuel cell stack 11and for supplying electricity to the drive motor 1 and the secondarybattery 3, reads signals from a variety of sensors included in theauxiliary equipment 12, executes the program concerned by anunillustrated CPU (Central Processing Unit) and the like, and sendscontrol signals to the auxiliary equipment 12.

The secondary battery 3 is supplied with electricity generated by thefuel cell system 2 and/or electricity regenerated by the drive motor 1,and is charged with the supplied electricity. When feeding the drivemotor 1 and the auxiliary equipment 12, the secondary battery 3discharges the stored electricity. These charge/discharge operations ofthe secondary battery 3 are monitored by the vehicle control unit 6 andcontrolled by control signals from the vehicle control unit 6.

The vehicle control unit 6 controls supply of the electricity generatedby the fuel cell system 2 or stored in the secondary battery 3 to thedrive motor 1, to have the drive motor 1 generate the required runningtorque. The vehicle control unit 6 controls switching operations of themain switch 4, and thus controls connections of the fuel cell system 2to the drive motor 1 and the secondary battery 3.

Moreover, the vehicle control unit 6 includes a vehicle start controlunit 21 which controls the fuel cell system 2 and the drive motor 1 atthe time when the fuel cell vehicle V starts running and the fuel cellstack 11 is started up. This vehicle control unit 6 stores, in anunillustrated storage unit such as ROM (Read Only Memory), programsdescribing a series of processing procedures for controlling the fuelcell system 2 and the secondary battery 3 and for supplying theelectricity to the drive motor 1, executes the programs by theunillustrated CPU and the like, and performs a vehicle start-upprocedure.

In the vehicle start-up procedure, when the fuel cell vehicle V isoperated to start running by a driver, electricity is fed to theauxiliary equipment 12 from the secondary battery 3 for starting up thefuel cell system 2. Then, after the start-up of the fuel cell stack 11is completed, the main switch 4 is turned to a closed position, and theelectricity supply from the fuel cell stack 11 to the drive motor 1 iscommenced. In the vehicle start-up procedure, it is computed, during atime period from the start of start-up operation of the fuel cell stack11 to turning the main switch 4 to the closed position, permissiontiming for the start of running by the drive motor 1 only by use of theelectricity of the secondary battery 3, and the upper limit of electricpower to be supplied from the secondary battery 3 to the drive motor 1.

[Vehicle Start-up Procedure]

Next, the steps of the vehicle start-up procedure in the fuel cellvehicle V will be described with reference to a flowchart of FIG. 2.

In the fuel cell vehicle V, when the vehicle control unit 6 detects, forexample, the ignition switch is turned on by a driver, a control signalfor starting the auxiliary equipment 12 to get the fuel cell stack 11ready for electricity generation is sent to the fuel cell control unit13. Then, the vehicle control unit 6 starts process of Step S1 in orderto compute running start permitting timing after the start of thestart-up operation of the fuel cell stack 11. Thereafter, in the vehiclecontrol unit 6, as will be described later, the drive motor 1 is fedwith electricity from the secondary battery 3, and the processes fromStep S1 onward are repeated until the fuel cell vehicle V startsrunning.

In the Step S1, the vehicle start control unit 21 reads out start-upstatus code SC, which is stored, for example, in an unillustratedmemory. This start-up status code SC is a code indicating a degree ofprogress in the start-up operation of the fuel cell stack 11 up tocompletion of the start-up operation. The start-up status code SC is setto become larger as the start-up operation progresses through awarming-up operation and the like by the vehicle start control unit 21.Here, the vehicle start control unit 21 receives information indicatinga start-up status of the fuel cell stack 11 from the fuel cell controlunit 13 which controls the auxiliary equipment 12 and fuel cell stack11, and updates the start-up status code SC.

Then, if it is determined, based on the value of the start-up statuscode SC, that the fuel cell stack 11 is in an initial state of thestart-up, where the electricity cannot be stably generated, that is, ifthe value of the start-up status code SC is equal to one preset as apredetermined value SC0 corresponding to the initial state of thestart-up, the vehicle start control unit 21 forwards the processing toStep S2. Meanwhile, if it is determined, based on the value of thestart-up status code SC, that a present state is not the initial stateof the start-up because Steps S2 to S4 have been performed in theprevious start-up procedure, the vehicle start control unit 21 forwardsthe processing to Step S5.

In Step S2, the vehicle start control unit 21 performs processing asshown in FIG. 3, and selects a start-up procedure of the fuel cell stack11. Specifically, in the vehicle start control unit 21, one start-upprocedure is selected from a plurality of preset start-up procedures A,B and C (Step S11). Then, the selected start-up procedure is determinedas the start-up procedure of the fuel cell stack 11, and a controlsignal which designates the start-up procedure is sent to the fuel cellcontrol unit 13 (Step S12).

Here, the vehicle start control unit 21 may select different start-upprocedures depending on ambient conditions of the fuel cell vehicle V,for example, depending on whether the ambient temperature is equal to ormore than a predetermined value. Alternatively, the vehicle startcontrol unit 21 may select different start-up procedures depending onwhether temperature of pure water for regulating the temperature of thefuel cell stack 11 is equal to or more than a predetermined value.

Next, the vehicle start control unit 21 reads the state of charge SOC ofthe secondary battery 3 in Step S3, and performs processing as shown inFIG.4 by use of the state of charge of the secondary battery 3 (StepS4), and thus obtains a running permission determining code SRUN forpermitting the fuel cell vehicle V to start running only by use of theelectricity discharged from the secondary battery 3.

Specifically, first as shown in FIG. 5, the vehicle start control unit21 refers to map data in which the relationship between the state ofcharges SOC0 of the secondary battery 3 at the time of starting up thefuel cell stack 11 and running permission codes SRC are set for eachstart-up procedure. Then, as the state of charge SOC of the secondarybattery 3 becomes higher, the vehicle start control unit 21 sets lowerthe running permission codes SRC for permitting the fuel cell vehicle Vto run by use of the electricity of the secondary battery 3. Moreover,the vehicle start control unit 21 computes a running permission code SRCaccording to the start-up procedure selected in Step S2 and the state ofcharge SOC to the secondary battery 3, which has been detected in StepS3 (Step S21 in FIG. 4). Then, the vehicle start control unit 21 setsthe obtained running permission code SRC as the running permissiondetermining code SRUN for determining in the following Steps S5 and S6whether the fuel cell vehicle V is allowed to start running (Step S22).

In the next Step S5, the vehicle start control unit 21 determineswhether the start-up status code SC is equal to or larger than therunning permission determining code SRUN set in Step S4. Thus, thevehicle start control unit 21 determines whether the start-up statuscode SC indicating the start-up status of the fuel cell stack 11 hasbecome the running permission determining code SRUN, and determineswhether to permit the fuel cell vehicle V to run by use of theelectricity of the secondary battery 3. If the start-up status code SChas become the running permission determining code SRUN, the vehiclestart control unit 21 determines to permit the fuel cell vehicle V torun, and forwards the processing to Step S6.

In Step S6, the vehicle start control unit 21 determines whether thestart-up status code SC is equal to the running permission determiningcode SRUN. When determining that the start-up status code SC and therunning permission determining code SRUN are equal to each other, thevehicle start control unit 21 forwards the processing to Step S7, andwhen determining that the start-up status code SC is larger than therunning permission determining code SRUN, the vehicle start control unit21 forwards the processing to Step S8.

In Step S7, the vehicle start control unit 21 performs processing asshown in FIG. 6, and thus computes an upper limit value of the electricpower to be extracted from the secondary battery 3 and fed to the drivemotor 1 when allowing the drive motor 1 to generate a driving torque forrunning only by use of the electricity discharged from the secondarybattery 3.

Specifically, the vehicle start control unit 21 refers to map data setfor each start-up procedure as shown in FIG. 7, in which therelationship between the start-up status codes SC and time to completionof the start-up operation of the fuel cell stack 11 are set. Then,according to the start-up procedure selected in the previous Step S2 andthe start-up status code SC determined equal to the running permissiondetermining code SRUN in Step S6, the vehicle start control unit 21computes the remaining time TS to the completion of the start-upoperation of the fuel cell stack 11 with reference to the map data inFIG. 7 (Step S14 in FIG. 6). Here, as shown in FIG. 8, the times TS fromthe time T1 when the start-up status codes SC became the runningpermission determining codes SRUN to the completion of the start-upoperations differ depending on the start-up procedure selected in theprevious Step S2, and different values for each start-up procedure willbe set.

Next, the vehicle start control unit 21 detects the state of charge ofthe secondary battery 3 at the present moment, and by use of the SOC(SOC1) of the secondary battery 3 and the time TS to the completion ofthe start-up, performs a computation as shown in the followingExpression 1:MAXP=KP×(SOC1−BSOC)/TS  (Expression 1)Thus, the vehicle start control unit 21 computes the upper limit valueMAXP of the electric power to be discharged from the secondary battery 3(Step S7). With regard to the upper limit value MAXP, the electricenergy required for starting up the fuel cell stack 11 is subtractedfrom the electric energy stored in the secondary battery 3, which can becalculated from the present state of charge of the secondary battery 3,electric energy obtained by the subtraction is defined as the electricenergy available for the running of the fuel cell vehicle V, and theavailable electric energy is divided by the time TS, thus electric power(electric energy per unit time) in the time TS is obtained.

Here, BSOC in the above-described Expression 1 is a preset value of SOCof the secondary battery 3, which is desired to be retained at the timeof completing the start-up of the fuel cell stack 11. BSOC may beadjusted according to the ambient temperature of the fuel cell vehicle Vand the temperature of pure water in the auxiliary equipment 12, usingtable data for starting up the fuel cell stack 11 stored in the vehiclestart control unit 21.

Moreover, the KP in the foregoing Expression 1 is previously obtained byperforming a computation as shown in the following Expression 2:KP=PB1×T1/ΔSOC  (Expression 2)Here, this Expression 2 determines the KP by use of the decrease ΔSOC ofthe SOC in the case the secondary battery 3 is discharged at thepredetermined electric power PB1 for a predetermined time T2 as shown inFIG. 9. Then, in this Step S7, the computation of Expression 1 will beperformed by use of the KP previously obtained.

Moreover, in this Step S7, the relationship between the remaining timeTS to the completion of the start-up and the upper limit value MAXP ofthe electric power to be discharged from the secondary battery 3 may bepreviously stored as map data, as shown in FIG. 10, and the upper limitvalue MAXP of the electric power to be discharged from the secondarybattery 3 may be obtained with reference to the map data shown in FIG. 7and the map data shown in FIG. 10.

In the next step S8, the vehicle start control unit 21 allows thesecondary battery 3 to discharge electricity to the drive motor 1,keeping the main switch 4 in the opened position, and permits the fuelcell vehicle V to run by use of the electricity from the secondarybattery 3. Here, when the start-up status code SC and the runningpermission determining code SRUN are equal to each other, the vehiclestart control unit 21 allows the secondary battery 3 to dischargeelectricity at the upper limit value MAXP set in Step S7. Moreover, inStep S8 after the fuel cell vehicle V is permitted to run by use of theelectricity discharged from the secondary battery 3, the vehicle startcontrol unit 21 may compute the upper limit value MAXP with reference toa map data as shown in FIG. 10, depending on the remaining time TS tothe completion of the start-up operation.

Then, in Step S10, the vehicle start control unit 21 determines whetherthe fuel cell stack 11 has become ready for electricity generation,based on the information indicating the start-up status of the fuel cellstack 11 sent from the fuel cell control unit 13. Thus, the vehiclestart control unit 21 determines whether the start-up of the fuel cellstack 11 has been completed. When the start-up has not been completed,the vehicle start control unit 21 forwards the processing to Step S11,and when the start-up is determined to complete, completes theprocessing.

Meanwhile, in Step S9 after it is determined in Step S5 that thestart-up status code SC is smaller than the running permissiondetermining code SRUN, the fuel cell vehicle V is not permitted to startrunning only by use of the electricity from the secondary battery 3.Then, in Step S1, the vehicle start control unit 21 receives theinformation indicating the start-up status of the fuel cell stack 11from the fuel cell control unit 13, and thus updates the start-up statuscode SC. Thereafter, the processing is repeated again from Step S1.Here, the vehicle start control unit 21 may have the auxiliary equipment12 consuming a large amount of power, such as a compressor, to startafter the fuel cell stack 11 reaches a predetermined state, and may setthe start-up status code SC equal to the running permission determiningcode SRUN after the compressor starts.

In such a manner, in Step S8, the vehicle start control unit 21 willpermit the fuel cell vehicle V to run by use of the electricity from thesecondary battery 3, and will repeat the processes from Step S1 onwarduntil the start-up of the fuel cell stack 11 is completed. Moreover,even after the secondary battery 3 is allowed to discharge and the fuelcell vehicle V starts running, the vehicle start control unit 21 willrepeat the update of the start-up status code SC until the completion ofthe start-up of the fuel cell stack 11.

According to the fuel cell vehicle V, the vehicle start-up processingdescribed above are performed, and thus, as shown in FIGS. 11A to 11D,first, at time t0 when the power source of the fuel cell vehicle V isturned on by an operation of the driver, the start-up status code SC is“0” (FIG. 11A), and the value of the SOC of the secondary battery 3 isthe SOC0 (FIG. 11D). In such a state, in order to start up the fuel cellstack 11, at time t1, supply of the electricity from the secondarybattery 3 to the auxiliary equipment 12 is started, the auxiliaryequipment 12 is controlled by the fuel cell control unit 13, andstarting up the fuel cell stack 11 in any one of the start-up proceduresis commenced. In such a manner, in the fuel cell vehicle V,charge/discharge status of the secondary battery 3 turns to adischarging state (FIG. 11B), and the voltage and SOC of the secondarybattery 3 start being lowered (FIGS. 11C and 11D).

Then, in the fuel cell vehicle V, the start-up status code SC isgradually increased as the start-up of the fuel cell stack 11 progresses(FIG. 11A), and when the start-up status code SC becomes equal to therunning permission determining code SRUN at time t2, supply of theelectricity from the secondary battery 3 to the drive motor 1 isstarted, and the fuel cell vehicle V starts running.

Thereafter, based on the remaining time TS to the completion of thestart-up and referring to, for example, a map data in FIG. 10, the upperlimit value MAXP of the electric power to be discharged from thesecondary battery 3 to the drive motor 1 and the start-up status code SCare repeatedly updated. Then, when the start-up status code SC reaches avalue indicating the completion of the start-up of the fuel cell stack11 at time t3, supply of the electricity from the secondary battery 3 tothe drive motor 1 is stopped. Note that, after the fuel cell vehicle Vstarts running only by use of the electricity of the secondary battery3, the vehicle start control unit 21 may update the start-up status codeSC and the upper limit value MAXP of the electric power to be dischargedfrom the secondary battery 3 according to state of power generation(fluctuations of cell voltages or rate of voltage increase) of the fuelcell stack 11.

Moreover, at the time t3 and after, the main switch 4 is turned from theopened position to the closed position, supply of the electricity fromthe fuel cell stack 11 to the drive motor 1 is started, and charging thesecondary battery 3 is started.

According to the fuel cell vehicle V to which the present invention isapplied, when the fuel cell vehicle V starts running using only theelectricity supplied by the secondary battery 3 to the drive motor 1,the electricity discharged from the secondary battery 3 is supplied tothe auxiliary equipment 12 to start up the fuel cell stack 11, and whenthe start-up status code SC shows that the start-up status of the fuelcell stack 11 has reached the predetermined state, the upper limit valueMAXP of the electric power to be extracted from the secondary battery 3is set based on the electricity charged in the secondary battery 3 andthe remaining time TS to the completion of the start-up of the fuel cellstack 11. The electric power of the upper limit value MAXP thus obtainedis supplied to the drive motor 1 from the secondary battery 3,accordingly the overdischarge of the secondary battery 3 can beprevented and torque required for the running of the fuel cell vehicle Vcan be securely obtained, in the case the fuel cell vehicle V is allowedto start running only by use of the electricity charged in the secondarybattery 3 during the start-up of the fuel cell stack 11. Moreoveraccording to the fuel cell vehicle V, since the electricity supply tothe drive motor 1 from the secondary battery 3 is started as soon as thestart-up status of the fuel cell stack 11 reaches the predeterminedstate, time to start of running can be reduced.

Specifically, according to the fuel cell vehicle V, the upper limitvalue MAXP of the electric power to be discharged from the secondarybattery 3 is determined during the start-up of the fuel cell stack 11,and the electric power of the upper limit value MAXP thus obtained issupplied to the drive motor 1. Accordingly, the electric power can besupplied to the auxiliary equipment 12 and the drive motor 1 withoutoverdischarging the secondary battery 3. Hence, according to the fuelcell vehicle V, it is not necessary to increase the capacity of thesecondary battery 3, and further, a necessity of an operation to storemuch electric power in the secondary battery 3 when the fuel cell stack11 is stopped can be eliminated.

Moreover, according to this fuel cell vehicle V, as described withreference to FIGS. 5 and 7, the running permission code SRC at the timeof starting up the fuel cell stack 11 is set based on the amount of theelectricity charged in the secondary battery 3, and the time TS to thecompletion of the start-up of the fuel cell stack 11 is set according tothe start-up status code SC. Accordingly, for example, even if start-uptime of the fuel cell stack 11 varies due to ambient conditions and thelike, the fuel cell vehicle V can start running without overdischarge ofthe secondary battery 3.

Furthermore, according to this fuel cell vehicle V, since the upperlimit MAXP of the electric power to be discharged from the secondarybattery 3 is set low when the state of charge of the secondary battery 3is low before starting, the overdischarge of the secondary battery 3 canbe prevented irrespective of the state of charge of the secondarybattery 3.

Still further, according to this fuel cell vehicle V, the upper limitvalue MAXP of the electric power to be discharged from the secondarybattery 3 can be limited in consideration of the time to the completionof the start-up of the fuel cell stack 11, and accordingly, an upperlimited value MAXP suitable for preventing the overdischarge of thesecondary battery 3 can be computed.

Yet further, the fuel cell vehicle V can be allowed to start runningafter the electricity is supplied from the secondary battery 3 to theauxiliary equipment 12 consuming much power. Accordingly, theoverdischarge of the secondary battery 3, which may be caused byconcurrent electricity consumptions of the drive motor 1 and theauxiliary equipment 12, can be prevented.

Yet still further, according to the fuel cell vehicle V, even when adifferent start-up procedure is selected according to the ambientconditions of the fuel cell vehicle V in order to reduce time to startrunning, the time TS to the completion of the start-up and the upperlimit value MAXP of the electric power to be discharged from thesecondary battery 3 can be set corresponding to the start-up procedureconcerned. Accordingly, even when the start-up procedure varies, theoverdischarge of the secondary battery 3 can be prevented. For example,when the fuel cell stack 11 is started up in a below-freezing condition,the electric power consumption of the auxiliary equipment 12 differsfrom usual one because of an additional step of melting pure ice and soon or some other reasons. Even in this case, according to the fuel cellvehicle V, the start timing of the running by use of the secondarybattery 3 can be adjusted appropriately from a viewpoint of the electricpower consumption.

The present disclosure relates to subject matters contained in JapanesePatent Application No. 2003-304091, filed on Aug. 28, 2003, thedisclosure of which is expressly incorporated herein by reference in itsentirety.

The preferred embodiment described herein is illustrative and notrestrictive, and the invention may be practiced or embodied in otherways without departing from the spirit or essential character thereof.The scope of the invention being indicated by the claims, and allvariations which come within the meaning of claims are intended to beembraced herein.

INDUSTRIAL APPLICABILITY

When the start-up status of the fuel cell reaches the predeterminedstate, the control apparatus according to the present invention sets theupper limit value of the electric power to be discharged from thesecondary battery based on the amount of electricity charged in thesecondary battery and the time to the completion of the start-up of thefuel cell, and allows the driving torque to be generated by supplyingthe electric power of the upper limit value from the secondary batteryto the drive motor. Hence, in the vehicle having the fuel cell mountedthereon, the present invention can be applied to a technology forensuring the torque required for the running of the vehicle whilepreventing the overdischarge of the secondary battery when the vehiclehaving the fuel cell mounted thereon is allowed to start running only byuse of the electricity charged in the secondary battery during thestart-up of the fuel cell.

1. A control apparatus for a vehicle which comprises a fuel cell forgenerating electricity, auxiliary equipment of the fuel cell, asecondary battery to be charged with electricity generated by the fuelcell, and a motor to be fed with electricity from the fuel cell and/orthe secondary battery, wherein the control apparatus commences start-upof the fuel cell, supplying electricity from the secondary battery tothe auxiliary equipment, monitors status of the fuel cell, and as thestatus meets a predetermined condition, computes an electric power atwhich the secondary battery discharges electricity, based on state ofcharge of the secondary battery and remaining time to completion of thestart-up of the fuel cell, and supplies electricity from the secondarybattery to the motor at the computed electric power.
 2. The controlapparatus according to claim 1, wherein the predetermined condition isbased on the state of charge of the secondary battery.
 3. The controlapparatus according to claim 1, wherein the electric power is computedin the case the motor is fed with electricity from the secondarybattery.
 4. The control apparatus according to claim 1, wherein theelectricity from the secondary battery is supplied to power-consumingauxiliary equipment before the motor.
 5. The control apparatus accordingto claim 1, wherein the start-up of the fuel cell can be executed in aplurality of procedures, one of the procedures is selected depending onambient conditions of the vehicle, and the predetermined condition isset for each procedure.
 6. The control apparatus according to claim 5,wherein the remaining time to completion of the start-up of the fuelcell is set for each procedure.
 7. The control apparatus according toclaim 5, wherein the ambient conditions comprise ambient temperature ofthe vehicle.
 8. A method for starting up a vehicle which comprises afuel cell for generating electricity, auxiliary equipment of the fuelcell, a secondary battery to be charged with electricity generated bythe fuel cell, a motor to be fed with electricity from the fuel celland/or the secondary battery, the method comprising: commencing start-upof the fuel cell, supplying electricity from the secondary battery tothe auxiliary equipment; monitoring status of the fuel cell; computingan electric power at which the secondary battery discharges electricity,based on state of charge of the secondary battery and remaining time tocompletion of the start-up of the fuel cell, as the status meets apredetermined condition; and supplying electricity from the secondarybattery to the motor at the computed electric power.